1921] Smiley: Flora of the Sierra Nevada of California 53 



such as Grizzly Peak, Penman Peak, Mt. Jackson, show Canadian 

 elements.''° Eastward of Sierra Buttes in Lincoln Valley (about 

 6,800 feet) the Canadian forest is well developed, the Murray Pines 

 being of large size,*'^ To the south of the Sierra-Nevada County line, 

 as the general altitude of the country rises, the Canadian life-zone 

 becomes of greater extent and forms a continuous belt on both sides 

 of the main divide with extensions westward to Snow Mountain and 

 to the numerous high peaks and ridges in the vicinity of English 

 Mountain. In this section the line separating the Transition and 

 Canadian floras runs at about the elevation of the surface of Lake 

 Tahoe (6,225 feet), Jeffrey Pine being the dominant tree at the south 

 end of the lake and on the Nevada side. The variation in this district 

 in the elevation of the Transition-Canadian boundary amounts to 

 some 300 feet. In the Yosemite district, nearly all the country 

 lying above the valley rim is Canadian ; the line marking the lower 

 boundary of the boreal region, north of the valley, ninning at about 

 6,700 feet on Snow Creek Trail above Mirror Lake and slightly higher 

 on the Eagle Peak Trail. On the eastern flank, above Mono Lake, the 

 same break occurs at approximately 7,500 feet or about 1,000 feet 

 above the lake itself. South of the Yosemite district, the dividing line 

 rises to 7,000 feet in Madera and Fresno counties and, in the extreme 

 south of the high Sierra, about Mineral King, one meets the typical 

 high mountain flora at nearly 8,000 feet, while to the east along the 

 Sierran main crest, the Transition flora maintains itself at elevations 

 of 9,000 or 9,500 feet on western slopes.* On the eastern flank in 

 Mono County, the boreal region extends down the flank to about the 

 level of Lake Sebrina (9,170 feet) where Yellow and Murray pines 

 grow together"^ and on the west side of Owens Valley, opposite Lone 

 Pine, to the 10,000-foot contour.*^^ The upper limit of the zone, which 

 corresponds to the lower boundary of the Hudsonian, similarly rises 

 from an altitude of about 6,500 feet in the mountains of northern 

 Plumas County and to 7,500 feet in the region of the Sierra Buttes. 

 West of Lake Tahoe, the Canadian-Hudsonian boundary varies be- 

 tween 8,000 and 8,500 feet in altitude; east of the Lake, in the Carson 

 Range, the upper limit of the Canadian is higher, on Mt. Rose*'* at 

 about 9,000 feet. This last elevation is in agreement with the average 



* For many details concerning plant distribution in the Sierra of eastern 

 Tulare County, a region not yet visited by me, I am indebted to the excellent 

 field notes made by the late Professor W. E. Dudley, of Stanford University, who 

 made a number of collecting trips into the region from 1895 to 1904, and also to 

 Dr. H. M. Hall, whose collecting trips have covered all the region considered in 

 this report. 



